Insulated electric conductor



(No Model.)

J. B. WILLIAMS.

INs-ULATBD ELECTRIC CONDUCTOR.

Patented May 5, 1891.

loaf UNITED STATES PATENT OFFICE.

JAMES B. IVILLIAHS, OF OAKLAND, CALIFORNIA.

INSULATED ELECTRIC CONDUCTOR.

SPECIFICATION forming part of Letters Patent No. 451,587, dated May 5, 1891.

Application filed November 13,1890. Serial No. 371,330. (No model.)

To @ZZ whom it may concern:

Beit known that l, JAMES B. WILLIAMS, a citizen of the United States, residing at Oakland, Alameda county, California, have invented certain new and useful Improvements in Insulated Electric Conductors; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the vaccompanying drawings, and to the letters marked thereon, which form part of this specification.

My invention relates to insulated electric conductors; and its novelty consists in the means elnployed to keep the conductor substantially concentric with the dielectric employed to insulate it when the said dielectric is composed in Whole or in part of vulcanized materials and is softened by the action of heat.

The insulated electric conductors referred to consist of a central metallic conductor, Which may be solid, stranded, or tubular, and which is substantially circular in crcsssee tion, surrounded by a dielectric which is itself usually surrounded by one or more Water-proof protecting-coverings.

Dielectrics maybe divided into two classesthose which are simple or formed of a homogeneous material and those which are compound or composed of layers of different materials-for instance, an inner layer of one kind of material and au outer of another kind. These may have an inner layer of unvulcanized material and an outer layer of vulcanized material, or they may both be of vulcanized material, in which case they should be of different kinds. An example of the former is a dielectric composed of an inner layer of a rubber composition containing` no sulphur and an outer layer of one containing sulphur, and an example of the latter is a dielectric composed of an inner layer of a rubber composition containing sulphur and au outer layer of a gutta-percha composition containing sulphur. In all cases the outer layerof a compound dielectric should be relatively thin.

Under the usual conditions of use to Which insulated electric conductors are subjected it will occur at times, either through outside influences or from the passage of currents of unusual strength through the conductor, that the dielectrics Will become heated and softened, and thus offer less resistance to the weight of the cond uctor,which gradually sinks down until it comes into sufficiently close contact with the exterior surface of the dielectric so as to destroy its value. This is especially apt to occur where conductors of great length are employed and which rest against hard substances, such as pipes in the ground and the like.

p My invention has for its object the overcoming of this difficulty by keeping the conductor in position and substantially concentric with its dielectric under conditions when the material of the dielectric will itself become soft.

In an application for Letters Patent of the United States tiled by me July 12, 1800, Se rial No. 358,571, l have described and claimed as my invention in general terms a centering device composed of fibrous material saturated with an insulating material not so readily softened by heat as the material of the dielectric, and also the specific combination of such a centering device with the conductorl provided with an unvulcanized dielectric.

The subject of the present application may be considered as an improvement upon or modification of the invention described in that application, and relates more particularly to the combination, with the conductor, of the centering device, hereinafter described, when the dielectric is in whole or in part composed of vulcanized material. Such dielectrics, while not so readily softened by heat as those composed of unvulcanized material, are subject to almost the same disadvantages in use.

l/Vhile insulated electric conductors provided With vulcanized dielectrics have been in common use for many years, heretofore there has been no means known to me Whereby the conductors could be kept in the center of their surrounding dielectrics when heated sufficiently to soften the latter, and the value of a centering device in this connection Will be at once apparent to any one familiar with the conditions under which such insulated electric conductors are used.

l accomplish my purpose by placing around the conductor and embedded in the dielectric ICO a centering device composed of fibrous material saturated with a suitable insulating material, preferably by means of a volatile solvent not injuriously affected by sulphur during the process of vulcanization, and preferably not so readily softened by heat as the materials composing the dielectric employed in each case, and so arranged that it is in contact with the conductor at as few points as possible, still retaining its function of support. The simplest form of this centering device is a yarn or cord of fibrous material previously saturated with an insulating ma terial not so readily softened by heat as the materials composing the dielectric, and also such as is not injuriously affected by sulphur during the process of vulcanization, such as cotton yarn saturated with shellac dissolved in alcohol. This device is in the majority of cases wound around the conductor and suitably secured thereto when necessary before the application of the dielectric. Then when the dielectric and its external water-proof covering have been applied and the conductor is heated from any cause sufliciently to soften the dielectric the material with which the centering device is saturated is not softened and the conductor is kept in place.

In the drawings, in which the same letters refer to the same parts in all of the iigures, Figure l is a transverse section of an insulated electric conductor provided with my centering device in its simplest form and showing a simple dielectric completely surrounding the same. Fig. 2 is a similar view ofthe same with a protecti11g-covering placed between the dielectric and its external waterproof protecting-covering. Fig. 3 is a similar view showing a compound dielectric; and Fie'. 4; is a central longitudinal section of the device shown in Fig. l, the parts in all of the figures being shown in relative positions, but not necessarily in relative sizes.

In the drawings, lV is the conductor surrounded by the dielectric I, composed of vulcanized materials and inclosed in a waterproof protecting-covering L, usually made of lead. S is a centering` device, consisting of a cord or cords wound around the conductor in the manner shown.

P is a protecting-layer surrounding the dielectric and placed inside of the protectingcovering L after the dielectric and centering device have been placed in position and are ready for use, and is preferably madeof fibrous material saturated with a suitable insulating material.

I is a compound dielectric, consisting of an inner layer t' of unvulcanized material and an outer layer t" of vulcanized material.

The manner of placing` my centering device in position in its simplest form-that of a spiral-when the dielectric is compound and has an inner layer of unvulcanized material and an outer layer of vulcanized material is as follows: The fibrous material of which the cord is composed is thoroughly and com pletely saturated with its insulating material, so that its intersticcs are yiilied with the solid particles of the same, and while this is in a plastic state the cord is applied to the conductor in aspiral form. The pitch of the spiral will depend in each instance upon the thickness and kind of material used as a dielectric, the size of the conductor, and the conditions under which the insulated conductor is to be used. For instance, if the insulated conductor is to be kept straight, or nearly so, and is to be used in comparatively cool situations, the pitch of the spiral should be steeper than when it is to be frequently bent or used in situations where it lis liable to become heated. An intelligent and skilled workman can readily determine the pitch of the spiral in each instance, and no fixed rules therefor can be given. Then the centering device has been so applied and suitably secured to the surface of the conductor by cement, if the insulating material with which itis saturated does not act in that capacitya layer of the unvulcanizable portion of the dielectric is placed by means of suitable apparatus upon the entire surface of the conductor which is to be insulated, so as to embed the centering device therein, and the vulcanizable layer, which should be relatively thin, is then placed in position around it in the manner well known to the art.

Then the dielectric is simple, the most satisfactory way of applying the centering device, if in the form of a spiral, is in many cases to force it into the dielectric after the latter has been applied to the conductor and while it is in a plastic state and before its vulcanization. When itis to be thus applied, usually by means of rolls, great care should be taken to completely saturate the brous material with the insulating material employed, so that its interstices will be completely filled with the solid particles of the same.

After the centering device has been placed in position the dielectric is vulcanized under pressure in the usual manner. In themajor-ity of cases it is advisable to protect the dielectric during vulcanization from the action of moisture by a sheath of tin, which is afterward removed. After vulcanization, if any spaces should be found to exist in the dielectric they should be iilled with parafiine or some suitable material. 'lhe finished conductor is then provided with its external pro teeting water-proof covering or coverings, as may be deemed desirable.

It is evident that wide modifications in detail may be made in my invention, especially in the form and materials used for the cen tering device, without departing from its essential features. I may make this device in the form of an open braid, or almost any practical structure having raised portions, and I may use any of the well-known fibrous materials and insulating materials suitable for the accomplishment of my purpose; but,

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however the device is formed or of whatever materials, its outer surfaces must be substantially cquidistant from the axis of the conductor, and it must be ot' such a nature that the insulating material With Which it is saturated Will not be injuriously affected by sulphur during vulcanization, and which will preferably require a higher temperature to soften it than that required to soften the dielectric inwhich it is embedded.

l. In an insluated electric conductor, the combination, with a central metallic conductor provided with a vulcanized dielectric, ot' a centering device also surrounding the conductor and embedded in the dielectric and composed of fibrous material saturated with an insulating material not injuriously affected by sulphur during the process of vulcanization.

2. In an insulated electric conductor, the combination, with a central metallic conductor provided with a compound dielectric wholly or partly composed of vulcanized materials, of a centering device also surrounding the conductor and embedded in the dielectric and consisting of fibrous material saturated with an insulating material not injuriously affect-ed by sulphur during the process of vulcanization.

3. In an insulated electric conductor, the combination, with a central metallic conductor provided with a vulcanized dielectric, of a centering device also surrounding the conductor and embedded in the dielectric and consisting of fibrous material saturated with an insulating material not so readily softened by heat as the materials composing the dielectric.

i. The combination, with an electric conductor provided with a compound dielectric, the inner layer of which is composed of unvulcanized material and the outer layer of vulcanized material, ot a centering device consisting of fibrous material, also surrounding the conductor and embedded in the dielectric and saturated with an insulating material not so readily softened by heat as the materials composing the dielectric.

5. The combination, with an electric conductor provided with a dielectric composed of vulcanized material and a centering device embedded within the same and consisting of iibrous material saturated with an insulating material not so readily softened by heat as the materials composing the dielectric, of a layer ot' fibrous material surrounding the dielectric and saturated with a suitable protecting insulating material, as shown.

6. The combination, with an. electric cond uctor provided with a surrounding compound dielectric having an inner unvulcanized and an outer vulcanized layer and in which dielectric is embedded a centering device also surrounding` the conductor and consisting of ibrous material saturated with an insulating material not so readily softened by heat as the materials composing the dielectric, of alayer of fibrous material surrounding the dielectric and saturated with a suitable protecting insulating material, as shown and described.

In testimony whereof I afiix my signature in presence of two witnesses.

JAMES 13. WILLIAMS. Vitnesses:

WM. RAIMOND Brunn, Jas. P. Downs. 

